PANAMA CANAL

the construction period of the panama canal covered about 10 years, but the actual work of construction was accomplished in about seven years; the first three years were devoted to preliminary preparation, during which time the thorough sanitation of the canal zone was ac- complished, yellow fever banished, an operating plant assembled, a working force gathered, living quarters erected and a food supply provided. reservoirs were built which furnished an ample supply of pure water to the canal force, and to the cities of col6n and panama, in which water- and sewer-systems were built. an out-of-date railway system was converted into an adequate one with a thoroughly modern equipment of rails, locomotives and cars. beginning of the work.—the first commission was in office only a year (1904-5) and accomplished little beyond formulating plans and ordering necessary supplies. the second, with john f. stevens as chief engineer and afterwards as chairman also, reconstructed the railway system, assembled the operating plant, collected an efficient working force and provided for it quarters, food and all necessary supplies. it also constructed wharves and docks at both terminals, and machine shops in which the locomotives, cars, steam shovels, etc., shipped in parts from the united states were put together. president roosevelt visited the isthmus in nov. 1906, the visit being notable as the first instance in which an american president had passed out of the u.s. territory while in office. col. goethals, of the engineer corps of the u.s. army, was appointed chairman and chief engineer of the third commission, on the resignation of mr. stevens (april 1 1907). this commission was composed of four army engineers, an army doctor, one navy engineer and one civilian. president roosevelt, who was convinced that the best results could not be obtained through an executive body of seven members, issued an executive order placing supreme power in the hands of col. goethals, abolishing the commission as an executive body, and making its members, who were heads of departments, subordi- nate to him, giving col. goethals all civil, military and other powers in the canal zone, and this course was subsequently approved in the act of 1912 for the government and operation of the canal after its completion. excavation and slides.—during the next five years 75% of the entire excavation of the canal was accomplished. the original plans provided for a total excavation of 95,000,000 cu. yd. and a total cost of $190,000,000 exclusive of $40,000,000 paid to the french canal company, $10,000,000 paid to the panama republic, and the cost of sanitation and civil administration. changes made in the basal dimensions with the approval of president roosevelt increased 32° the total excavations to 175,000,000 cu. yd. and the estimated cost to $375,210,000, inclusive of payments to the french canal co. and the kepublic of panama. when the canal was declared formally complete and opened by president wilson july 12 1920, a total of about 240,000,000 cu. yd. had been excavated and the total cost, exclusive of expenditure for naval and military defence, was only $366,650,000, of which $10,000,000 was for ‘‘ slides ’’ or breaks in walls of the cut of which there were about 30 at different times, affecting an area of 220 ac. and increasing the excavation by 30,000,000 cu. yards. i. engineering features gatun dam.—the panama canal is a huge water bridge rather than a canal, for its surface for the greater part of its length is 85 ft. above sea level and is held in place by dams at elther end. the largest and most important dam is at gatun, on the atlantic side. it spans the northern and lower end of a deep valley through which the chagres river formerly flowed to the sea. it is 13 m. long measured on its crest, half a mile wide at the base, 400 ft. wide at the water surface, 100 ft. wide at the top; and its crest is at an elevation of 105 {t. above sea-level. it is really two dams in one, for in its centre there is a natural hill or rock 110 ft. high. in this the spillway of the dam is constructed, and against its two sides rest the two sections of the great dam. the dam itself contains 23 million cu. yd. of material. its outer portions are composed of rock and earth mainly from the cut, and its centre or core of material drawn by hydraulic process from pits above and below the dam. this material is a natural mixture of sand and clay which in a watery condition flowed into the interstices of the rock and clay of the structure, making the whole at the centre a rubble-wall firmly cemented together and thoroughly impervious to water. of the entire length of the dam only soo ft. are exposed to the maximum waterhead of the lake, which is 85 to 87 feet. in 19109, after an exceptionally light rainfall, the maximum level of the lake was 87-16 ft. in dec.; and in may 1920, 81-65 feet. the spillway is a concrete-lined channel, 1,200 ft. long and 285 ft. wide, the bottom being 1o ft. above sea-level, sloping to sea-level at the lower end. across the lake-opening of the channel is a concrete dam in the form of an arc of a circle, making its length 808 ft., although it closes 2 channel with a width of only 285 feet. the crest of this dam is 69 ft. above sea-level, or 16 ft. below the normal level of the lake. on the crest are 13 concrete piers with their tops 115-5 ft. above sea-level, and between these are 14 regulat- ing gates of the stoney type which move up and down on roller trains in niches in the piers. the gates permit a discharge of water greater than the maximum known discharge of the cha- gres river during a flood. near the north wall of the spillway is a hydroelectric station capable of generating, through turbines which are supplied with water from the lake through a forcbay, sufficient electricity to meet all demands, including the lighting of the canal and all canal zone towns and buildings; the ma- chinery of the locks, the machine shops, dry-dock and coal- handling plant; and the telephone and telegraph systems. there is an emergency diesel electric plant at miraflores. dams on the pacific side—at pedro miguel, at the south or pacific end of the cut, the water is held at summit level (level of gatun lake and the cut, normally 85 ft. above the sea) by pedro miguel lock and two flanking dams extending from the side walls of the lock to hills on either side. the distance between the hills at elevation 92 [t. is 2,000 feet. the situation of the lock at the base of cerro luisa made it practicable to connect with that hill by a short concrete wall, 260 ft. in length, subsequently covered with earth. on the west side a rock and earthen dam was built with a puddled and rolled impervious core, 1,400 {[t. in length. the minimum width of base is 800 ft., the side slopes, 8 to 1, the top, 105 ft. above sea- level. the maximum head of water to which the dam is subjected is 40 ft., the average between 25 and 30 feet. the pedro miguel lock raises or lowers ships 31 ft.—the differ- ence between the summit level of 85 ft. and the normal surface of miraflores lake—s4 [t. above sea-level. the miraflores lake is a mile in length, and its waters are retained by the miraflores locks and flanking dams. the east dam at miraflores is of concrete, and the greater part of it is the spillway of miraflores lake. this spillway is 432 ft. in length, with the crest of its dam 38.67 ft. above sea-level, and the supporting piers for the gates rising to 85-17 ft. above sea- level. eight gates, similar to those in the gatun spillway, each 47 ft. panama canal 10} in. long by 19 ft. in height, and weighing 44 tons each are oper- ated in the same way as the £4 gates at gatun; but the dam at mira- flores is straight, instead of being in the form of an arc, as at gatun. the west dam at miraflores is of earth and rock and extends almost parallel with the axis of the locks to a hill to the south. its length is 2,300 {t., top 70 ft. above sea-level, width of top 4o ft., and slope of sides approximately 12 to 1. it contains 661,000 cu. yd. of soft hydraulic material and 1,500,000 cu. yd. of rock and earth. the locks.—all locks are in duplicate, constructed in the same manner, and their chambers, with walls and floors of concrete, have the same usable dimensions—1,000 ft. long and 110 ft. wide. there are six pairs, making 12 in all. the side walls are from 45 to 50 ft. wide at the surface of the floor, are vertical on the chamber side, and narrowed on the outside from a point 243 ft. from the floor, by means of a series of steps each 6 ft. long, to a width of 8 ft. at the top. a culvert 254 sq. ft. in cross-section, extends the entire length of each middle and side wall, and from each of these large culverts, smaller culverts, 33 to 44 sq. ft. extend to holes in the floors. fifteen feet above the top of the culvert in the middle wall there is a u-shaped space 19 ft. wide at the bottom and 44 ft. at the top. this space is divided into three storeys; the lowest for drainage; the middle for wires that carry the electric current to operate the gates and valve machinery installed in the centre wall; and the upper a passage-way for the operators. all lock walls are 81 ft. high, except in the lower pair of locks at miraflores, where they are 82 ft. because of the ex- treme tidal oscillations of about 21 [t. in the bay of panama. in the walls at gatun there are 2,068,000 cu. yd. of conercte, and in those on the pacific side 2,440,000 cu. yards. all lock walls rest on rock foundations. the approach wall at the north entrance at gatun, 1,031 ft. long, rests upon piles driven from 35 to 70 ft. into the earth; that at the south or lake entrance 1,009 f{t. long, rests on piles reach- ing to rock, in some places over roo ft. below sea-level. cellular form of reinforced concrete is used in all approach walls, except those of the lower locks at gatun and miraflores, where mass con- crete is used because of the effect of salt water on steel! reinforcement. lock gates.—-the lock gates, each composed of two leaves, are 65 ft. wide, from 47 ft. 4 in. to 82 ft. high, 7 ft. thick, and weigh from 390 to 730 tons. there are 92 leaves in all, and their combined weight 1s 60,000 tons. each isa huge webbed steel box, the girders of which are covered with a stecl sheathing. all portions of the interior are accessible, with watertight compartments providing for the adjust- ment of the buoyancy so as to control within limits the dead load on the bearings, making the leaf practically float in the water. this watertight compartment is subdivided vertically into three sections, each independently watertight, so that if the shell should be broken or leak, probably only one section would be affected. an air shaft, 26 in. in diameter, runs from the bottom compartment up to the top of the gate, and is also watertight where it passes through the upper half of the leaf, the girders are made with manholes through the webs, providing communication from the top to the bottom of the leaf, and are con- nected by several sets of vertical transverse diaphragms of solid plates, running from top to bottom of the leaf, thus making a cellular construction, and dividing the spaces between the horizontal girders into small pockets, all of which are accessible through manholes. each leaf rests at the bottom of its heel post upon a hemispherical pivot of forged nickel steel, and is hinged at the top to the masonry of the lock wall. it swings free on the pivot like a door, without wheels or other support beneath it. intermediate gates are used in all except one pair of locks, and divide the space into two chambers, one 600 and the other goo ft. in length. this makes possible a saving of water and time in locking small vessels through, for 95°, of the vessels navigating the hizh seas are less than 600 ft. in length. the highest gates and the highest lock walls on the canal are those of the lower locks at miraflores, and these locks are the only ones which have no intermediate gates. the total lift from mean sea-level to the level of miratlores lake, 54 ft., is divided equally between the upper and lower locks. the depth of water on the mitre sills is 4o feet. the locks are filled and emptied through the large and smaller culverts. the large culverts are controlled at points near the gates by large valves, and each of the small culverts feeds in both directions through the laterals, thus permitting the passage of water from one twin lock to another, effecting a saving of water if desired. the average time required to fill or empty a lock chamber is 8 min. if both centre and side wall culverts are used, and 12 min. if only one culvert is used. the average time to pass a vessel through the three flights at gatun locks is an hour, from arrival to clearance; for the one lift at pedro miguel half an hour, and for the two flights at miraflores three-quarters of an hour. the time of passage of a ves- sel from one terminal port of the canal to the other is 7 hours. the transit is conducted under a time schedule in order to use to best advantage the lock operating forces, assure safety in passing and conserve water in times of need. passage of locks.—with the exception of small craft no vessel can pass through the locks under its own power. on arrival at the locks it is taken in tow by towing locomotives or “ electric mules.’’ these locomotives opcrate on cog tracks on the lock walls at the rate of two m.an hour. the usual number required for a vessel is six: two ahead, one on cach wall, two slightly forward of amidships, one on each panama canal side, the four imparting forward motion to the vessel; and two astern, one on each side, to aid in keeping the vessel in a central posi- tion and in bringing it to rest within the chamber while the emptying or filling is carried on. smaller vessels are handled with four loco- motives, the two amidships being dispensed with; while very large craft may use cight. the movements of the locomotives are directed by the pilot from the bridge of the vessel. each locomotive is equipped with a slip drum, towing windlass and hawscr, which per- mit the towing line to be taken in or paid out without actual motion of the locomotive on the track. the locomotives run on a level, but in passing from one lock to another they climb heavy grades. before a lock can be entered, a fender chain, stretched across the walls of the approach, must be passed. if all is proceeding properly, this chain is dropped into its groove to the bottom of the channel. if by any chance the ship is moving too rapidly for safety, the chain remains stretched and the vessel runs against it. the chain, which is operated by hydraulic machinery in the walls, then pays out slowly by automatic release until the vessel is brought toa stop. the chain, which weighs 24,098 ib., and is stronger than any previously made, is capable of stopping a 10,000-ton ship running at 4 m. an hour within 73 ft. or less than the distance between the chain and the first gate. if the vessel should get away from the towing locomotive and, breaking through the chain, ram the first gate, there is a second gate 50 ft. away, protecting the lock, which arrests further advance. when the leaves of this gate swing open, the vessel is towed in, and the gate is closcd behind it. then, from 105 openings placed at regular intervalsin the lock floor, watcr pours in, lifting the vessel to the level of the lock above. this inilow, coming equally from all points, does not move the ship from a stable posi- tion. the gates are never opencd or closed with a head of water on either side of them. the process of lifting is repeated until the vessel reaches the lake level. at all times the vessel is in full view of the men who are controlling it and as safe as if ticd to a wharf. the gates are opened and closed by a powerful machine invented by edward schildhauer, an electrical engineer in the employ of the isthmian canal commission. it consists of a crank gear or wheel moving through an arc of 197°, placed horizontally in the lock wall. to the outer rim of the wheel is attached a strut or connecting rod which is fastened to the top of a lock gate 17 ft. from the pintle or hinge. when the wheel turns in either direction the gate leaf is opened or shut, the operation taking two minutes. the crank gear, constructed of cast stecl, 1s 19 ft. 2 in. in diameter and weighs approximately 35,000 pounds. it is connected with an electric mo- tor, and a small electric switch sets itin motion. every operation in the passage of a vessel through the lock, except the movements of the towing locomotives, is controlicd by one man in a building at the top of the centre wall commanding an unobstructed view of every part of the locks. ile has before him a control board table 64 ft. long and 54 ft. wide, which is a complete model of the locks in dupli- cate, with switches and indicators in the same relative positions the machines they control occupy in the lock walls. standing by this board the operator throws the electric switches, and in response to his action he sees in the model the fender chains rise and fall, the gates open and close, the water rise and fall in the locks, and knows the exact position of the vessel at every stage of its progress. each gate, each valve for ictting in the water to the culverts and each fender chain is operated by a separate motor mounted near the machinery in chambers in the lock wall. in each machinery chamber there is a starting panel containing contactors by which current is applied to the motor, and these panels in turn are controlled from a main unit in the central control house. some of the machinery chambers at gatun are 2,700 ft. distant from the point of control, 90 % of them are within 2,000 ft., and 50° within 1,200 fect. ii. course and accessories the length of the canal from shore line to shore line is 42 m., and from deep water in the atlantic to deep water in the pacific 50 miles. the canal does not, as is generally supposed, cross the isthmus from east to west. it runs due south from its en- trance in limon bay, through the gatun locks to a point in the widest portion of gatun lake, a distance of 113 m.; it then turns sharply toward the east and follows a course generally south- eastern till it reaches the bay of panama. its terminus near panama is about 225 m. east of its terminus near colen. in passing from the atlantic to the pacific a vessel enters the ap- proach channel in limon bay, which has a bottom width of 500 {t. and extends to gatun a distance of seven miles. at gatun it enters a series of three locks in flight which lilt it 8s feet. it then enters upon gatun lake, which covers an area of 164 sq. m. with a depth varying from 45 to 87 ft. and contains 183,136,000,- ooo cu. ft. of water. the canal has a channel varying from 500 to 1,000 ft. in width for a distance of 24 m. to gamboa, where the cut passage begins. through the lake a vessel may steam at full speed, without any risk. 30 the channel through the cut, a distance of about 8 m., has a bottom width of 300 ft. and a depth of 45 {t., and extends to the locks at pedro miguel, the pacific end of the water bridge. at pedro miguel the vessel is lowered in the single lock 31 ft. to a small lake, at an elevation of 54 ft. above sea-level, through which the vessel passes 1 m. to the two locks at miraflores. these drop it to sea-level, and through an approach passage § m. long, with a bottom width of 500, {t., it passes into the pa- cific. the cut has eight angles and at these the channel is widened sufficiently to allow a 1,000-ft. vessel to make the turn. the smallest angle is 7° 36’ and the largest 29° 59’. in the whole canal there are 22 angles, the total curvature being 600° 54’. the sharpest curve is 67° 11’. the canal is lighted from end to end by electricity and gas. there are concrete lighthouses for range lights on the hillsides, and beacons in the cut, in which electricity is used. the channel through gatun lake is marked with floating buoys lighted with compressed acetylene dissolved in acetone. the most powerful electric lights are those of the approach channels, which are visible for from 12 to 18 nautical miles. the beacons and gas-buoy lights are 850 candle-power. white and red lights are used, and in order to climinate the possibility of confusing the lights with one another, and with the lights on shore, all range lights, beacons and buoys have individual characteristics, formed by flashes and combinations of flashes of light and dark intervals. the electric lights on the locks are suspended from brackets on concrete columns 34 ft. high, and clustered under concrete hoods in such a way as to light the lock chambers and not penctrate along the axis of the canal. breakwaters—long breakwaters have been constructed near the approach channels in both oceans. one in limon bay, or colen harbour, called the west breakwater, extends from the bay from toro point at an angle of 42° 53’ northward from a base line drawn from toro point to colen light, and is 11,526 ft. in length, 15 ft. wide at the top and io ft. above mean sea-level. a second, also in limon bay, known as the east breakwater, is without land con- nection, one m, in length and runs in an easterly direction at nearly a right angle with the canal channel. it has a lighthouse on the channel end. the west breakwater protects the harbour against “ northers,"’ very severe gales which are likely to blow from oct. to january. the last breakwater prevents silting in the canal channel. the breakwater at the pacific entrance extends from balboa to naos i., a distance of 17,000 feet. it lies from 900 to 2,700 f{t. east of, and for the greater part of the distance nearly parallel to, the axis of the canal prism, varies from 20 to 40 ft. in height above mean sca-level and is from 50 to 3,000 ft. wide at the top. it was con- structed for a twofold purpose; first, to divert cross-currents that would carry soft material from the shallow harbour of panama into the canal channel; second, to furnish rail connection between the islands and the mainland. permanent canal buildings—upon the completion of the canal a number of villages along the line occupied during the construction days were abandoned, the sites of several being covered by the filling of gatun lake. the buildings in good condition were transferred to the permanent towns located at the ends of the canal and adjoining the locks. culebra, the former headquarters of operations, situated on the west bank of the cut near its deepest part, was turned into an army post. the permanent headquarters were located at balboa heights, and the offices of the departments centred in a large 3-storey con- crete administration building situated on a hill 100 ft. above sea-level, and overlooking the pacific entrance to the canal. on the hill in the rear of this building are the residences of the governor and other officials. on the low land in front of the building, in a site which was formerly a tidal swamp and was raised to 20 {t. above sea-level by filling with material from the cut and hydraulic fill from excavation in the harbour, is the town of balboa. this is laid out on both sides of a central avenue called the prado, and contains permanent buildings of concrete blocks roofed with red tile. in additien to the dwellings of employces there are a police station, post office, fire-station, sanitary office, dispensary, clubhouse, a community house con- ducted by the catholic church, an army and navy yo cal: restaurant, churches, lodge hall, schoolhouse and playground. effective municipal layout in a setting of great natural beauty 34 and an abundance of trees and shrubs make the villages very attractive places of residence. the streets are of concrete with asphalt surfacing, and the number of automobiles in use is noticeably large. terminal facilities.—at the ports on both oceans have been constructed facilities ample for commercial shipping and the naval needs of the united states. modern piers, 1,200 ft. in length by 240 ft. in width, with enclosed sheds, built of rein- forced concrete and steel, are ample for the transhipping of cargo and the storage of goods consigned there for orders. at the pacific end, at the foot of sosa hill, balboa, are marine and railway repair shops, foundry, etc., covering 60 ac., thoroughly equipped and including a dry dock having a usable length of 1,000 ft. and entrance width of r1o ft., capable, like the locks and other parts of the canal, of accommodating any vessel afloat. the depth over keel blocks is 43 ft. at mean tide. smaller shops and a dry dock 300 ft. long and 48 ft. wide with depth of 13} ft. are operated at the atlantic end. coaling plants capable of rapid bunkering are operated at both terminals, as well as oil-pumping plants connected with storage tanks for fuel oil, diesel oil and gasolene. storehouses supply all kinds of ship chandlery and repair material, as well as foodstuffs, beef and other fresh meats and cold storage supplies, ice, etc. ships’ every need of repair or supply can be met. radio stations for communication with ships are operated by the u.s. navy at cristobal and balboa, and also at cape mala, 90 m. south of the pacific entrance, and a high-power station, primarily for government communication with the united states, is situated at darien, midway of the isthmus. salvage tugs and other wrecking equipment are available for use of vessels within a radius of 1,000 m. or more of the canal. hotels and hospitals are situated at both terminals. fortifications and military occupation.—by executive order dated dec. 5 1912, president taft declared that ‘ all land and land under water within the limits of the canal zone are necessary for the con- struction, maintenance, operation, protection, and sanitation of the panama canal,” and title to all such land was acquired by the govt. of the united states. the canal zone is thus a military reservation, and the only activities carried on by other than govern- ment forces are on land rented to steamship interests and to agricul- turists under revocable licences. heavy fortifications have been built at both entrances to the canal and brigade posts established near the locks. both the army and the navy have aerial forces at the canal, and a base for submarines is maintained at the atlantic end. the total military force is 10,000 men. panama raiiroad.—the panama railroad extends between col6n and panama on the eastern side of the canal, and is 47-61 m. long. a branch line, extending from pedro miguel to las cascadas and crossing the canal on a floating bridge at paraiso, was discontinued jan. 1 1921. the railroad as built in 1850-5 followed the course of the chagres from gatun to gamboa, and was for the most part on the west side of the route of the canal. with the building of the canal it was necessary to relocate the railroad throughout practically its whole length. the construction of the original railroad was done by an american company in the years 1850-5 under great difficul- ties; its completion antedated by 14 years the completion of the first transcontinental railroad in the united states. at that time auges had not been standardised, and a width of 5 ft. was adopted or the panama railroad which has been maintained since. the railroad was an essential factor in the construction of the canal, and is an important adjunct to its operations. it is equipped with go-lb. rails, rock-ballasted track, and automatic signals. it uses modern american rolling-stock, including oil-burning locomotives. iii. administration and finance under an act of congress, approved aug. 24 1912, the pan- ama canal is governed and operated, and the canal zone is governed through a governor of the panama canal, appointed by the president, with the approval of the senate, for a term of four years, at a salary of $10,000 a year. in addition to the oper- ation of the canal, the governor has official control and jurisdic- tion over the canal zone and performs all duties in connection with its civil government, it being held, treated, and governed as an adjunct to the canal. there is one u.s. district court in the canal zone, with the same jurisdiction and procedure as the same courts in the united states, the judge of which is appointed by the president. appeals are made to the circuit court of appeals of the fifth circuit of the united states. at balboa panama canal and cristobal there is a magistrate’s court for minor cases, the judges being appointed by the governor. gen. goethals was the first governor and served until jan. 11 1917, when he resigned and was succeeded by col. chester harding, u.s.a., who held the office until march 27 1921, when he was succeeded by col. jay j. morrow, u.s.a. the latter resigned in oct. 1924, and was succeeded by col. meriwether l. walker, u.s.a. the organisation on the isthmus includes a number of depart- ments and divisions in charge of the various activities, as follows: dept. of operation and maintenance, including the marine div., mechanical div., dredging div., section of lock operation, electrical div., div. of municipal engineering, fortifications div., and several sections; the supply dept., made up of the quartermaster section, subsistence section, commissary div., cattle industry and plantations, and hotel washington; the accounting dept.; the health dept.; the ex- ecutive dept. and the panama railroad. the panama canal has an office in washington, d.c., and the panama railroad co. has an office at 24 state street, new york. canal zone population.—a census of the canal zone taken in 1925 showed a total population of 37,011, of which 27,151 were civilians and the remainder military. the civilians included 2,301 adult male americans, 2,413 american women, 2,399 american children, and people of other nationalities as follows: men, 6,928; women, 4,563; children, 8,547. : canal force-—the working force at the end of june 1925 num- bered 12,270, of whom 2,885 were amcricans, chiefly in official and clerical positions and skilled trades, and 9,385 were alien labourers, chiefly west indian negroes. the apparent discrepancy between these figures and those of the canal zone census is due to the fact that many of the labourers live in the cities of panama and colen, which are not within the canal zone. tolls —the hay-pauncefote treaty between great britain and the united states, abrogating and succeeding the clayton- bulwer treaty, was ratified on dec. 16 1901. it contained this clause: the canal shall be free and open to the vessels of commerce and of war of all nations observing these rules, on terms of entire equality, so that there shall be no discrimination against any such nation or its citizens or subjects in respect of the conditions or charges of traffic or otherwise. such conditions and charges of traffic shall be just and equitable. in 1912 congress passed an act for the operation and govern- ment of the panama canal, which was approved by president taft on aug. 24 of that year, and which contained the provision that “ no tolls shall be levied upon vessels engaged in the coast- wise trade of the united states.”” a formal protest against this exemption was made by great britain on the ground that it was a violation of the hay-pauncefote treaty. in june 1914, under a special appeal from president wilson, congress passed a bill which repealed the exemption act of 1912. this was approved by president wilson on june 1§ 1914. under authority given to him by the panama canal act of aug. 24 1912, president wilson issued a proclamation, on nov. 21 1913, fixing the canal tolls at $1.20 per net ton of net capacity as determined by the panama canal rules of measurement. on feb. 15 1915 president wilson issued supplementary instructions that where application of the $1.20 per-net-ton rate produced a sum in excess of the sum produced by the application of the $1.25 rate on net registered tonnage as determined by the u.s. rules of measurement, the excess amount should be uncollectable. the effect of this ruling was to reduce by approximately 14% the revenue from tolls paid by ships of all nationalities using the canal. during the first six years of operation there was a marked increase in traffic notwithstanding the fact that the world war everywhere prevented the normal development of ocean- going commerce. after the entry of the united states into the war there was a decrease in commercial traffic, due to the diver- sion of certain lines of ships to trans-atlantic service, which was more than offset by the increase in traffic growing out of the war, chiefly on account of the development of the nitrate trade with the pacific coast of south america. with the return of normal conditions after the war traffic rapidly increased. canal traffic.—the number of commercial transits, the amount received from tolls and other collections, and the current expenses of pan-american conferences maintenance and operation for the fiscal years ending june 30 1915- 25, are shown in the following table:— tolls and other transit revenues $ 4,343,383.69 2,558,542.38 5,808, 398.70 6,411,843.28 6,354,016.98 8,935,871.57 i2,040,116.70 11,385,592.32 17,691 ,844.06 24,681 ,853.89 21,582,618.16 current expenses of operation and maintenance number of commercial transits fiscal year $4,123,128.09 6,909,750.15 6,788,047.60 5,920,342.94 6,112,194.77 6,548,272.43 9,328, 300.14 7:919,017.63 7:090,777.56 1924 5,230 8,373,905.39 1925 4,673 8,116,693.44 among nations the chief users of the canal were the united states and great britain. the number of vessels passed each year for these nations and for all other nations was as follows:— 1915 igi6 1917 1918 igi9 1920 1921 1922 1923 1,072 760 1,806 2,068 2,028 2,478 2,892 2,736 3,967 all other nations 153 united states 479 238 464 628 786 1,129 1,210 1,095 1,994 2,947 ' 2,326 great - r fiscal year britain the following is the saving in nautical miles, effected by the pana- ma canal from european ports to ports on the west coast of america, to hawaii and to new zealand :-— to sitka, alaska port townsend, wash. .. portland, oregon san francisco, cal. . san diego, cal. acapulco, mexico san jose, guatemala honolulu, hawaii guayaquil, ecuador . callao, peru valparaiso, chile wellington, n.z. the following is the saving, in nautical miles effected by the panama canal in length of all-water routes between ports of the atlantic-gulf u.s. seaboard and various pacific ports:— to new gal- orleans] veston sitka, alaska portland, oregon san francisco, cal. . san diego, cal. acapulco, mexico san jose, guatemala honolulu, hawaii guayaquil, ecuador callao, peru valparaiso, chile yokohama, japan shanghai, china hongkong, china manila, p.1 ; . adelaide, s. australia melbourne, australia sydney, australia wellington, n.z. 1 distance less via suez. 30 the notable increase in business in 1924 was due mainly to the development of oil-fields in california, whence large quantities of crude oil were shipped in tank steamers to refineries on the atlantic seaboard. these shipments declined in the following year, but the loss was partly offset by the normal growth of other trades. public vessels of the united states, panama and colombia and vessels which are sent through the canal solely for repair at the balboa shops are exempt from the payment of tolls, and such vessels are omitted from the statistics in the above table. from the open- ing of the canal to june 30 1925, they numbered 2,613, the majority of them being american naval vessels or army transports. bibliography.—joseph bucklin bishop, the panama gateway (1913; rev. ed., 1915); george w. goethals, government of the canal zone (1915); w. l. sibert and john w. stevens, the construction of the panama canal (1915); w. c. gorgas, sanitation in panama (1915); joseph a. le prince and a. j. orenstein, amfosquito control in panama (1916); annual reports of the governor of the sl nar » dd. di,